Trunk Strength Research Articles

Assessment of isokinetic trunk muscle parameters, postural control and quality of life in sedentary and active older adults

ObjectiveThe study intended to evaluate the differences between active and sedentary postural control and isokinetic trunk strength. The secondary aim was to evaluate the participants' total physical activity (PA) score regarding the specific quality of life domains assessed. MethodsAn analytical cross-sectional study involving 64 participants of both sexes aged ≥ 60 years (60 to 86 years) was conducted. Habitual PA was assessed using the Baecke Modified Questionnaire for older adults, and participants were classified as active or sedentary. Quality of life was assessed using the SF-36 questionnaire, postural control was evaluated using a bipedal force plate, and trunk muscle strength was measured using an isokinetic dynamometer. The independent t-test, Spearman correlation, and Generalized Linear Model were employed, with a significance level of 5%. ResultsNo significant differences were observed in postural control between active and sedentary participants. However, significant differences were observed in the peak touch and mean power of trunk extensors and flexors at speeds of 60 and 180◦/s (p<0.005), except for the ratio between flexor and extensor muscle peak torque assessed at both speeds. Quality of life showed significant correlations with PA level regarding the domains of functional capacity, vitality, and health conditions. The logistic model revealed an association with the domains of functional capacity and pain in relation to PA. ConclusionOur results underscore the importance of regular PA practice for the older adult population, indicating the enhancement of health-related quality of life and the strength of trunk extensors and flexors.

Dynamometry for the Assessment of Trunk Muscle Strength in Postpartum Women with Pregnancy-Related Posterior Pelvic Girdle Pain: A Reliability Study

ObjectivesTo investigate the inter and intra-rater reliability of maximum isometric trunk muscular strength in postpartum women with pregnancy-related posterior pelvic girdle pain using a handheld dynamometer. MethodsThirty women (30.13 ± 3.67 years) with pregnancy-related posterior pelvic girdle pain (PPGP) had their trunk muscular strength assessed using a handheld dynamometer. Inter-rater reliability was estimated for measurements of two separate raters on the first day of the investigation. The tests were repeated with the first rater seven days later to determine the intra-rater reliability. A digital handheld dynamometer was used for testing, and a metal bar was used to secure it to a table. Participants were instructed to use maximal force to push the dynamometer in various trunk flexion, extension, lateral flexion, and rotational orientations. Each trial was repeated three times and averaged to obtain the representative assessment data. Analysis of variance, interclass correlation, absolute agreement, and standard error of measurements were used to evaluate the repeatability of measurements. ResultsExcellent inter and intra-rater reliability were demonstrated. The inter-rater reliability, computed with intraclass correlation coefficient (ICC), ranged from 0.979 to 0.992, and intra-rater reliability (ICC) ranged from 0.966 to 0.987. The standard error of measurement ranged from 0.35% to 1.26% for the different tests. Additionally, the dynamometer values in women with PPGP might be reported using just one trial after an instruction. ConclusionThe maximum isometric trunk muscular strength is reliable, and a quantitative assessment of the trunk strength in women with postpartum pregnancy-related posterior pelvic girdle pain and could be used to monitor the changes in postural stability between sessions.

Effects of a Specific Trunk and Shoulder Strength Training Program on Throwing Velocity and Accuracy: A Study Among Hungarian First-League Female Handball Players

The aim of the study was to record shoulder and trunk stability of elite female handball players and to investigate their effect on throwing velocity and accuracy. 151 female handball players (9 teams in total) from the Hungarian first league participated in a mid-season conditional survey. The study included tests of trunk and shoulder stability, and measurements of factors affecting shoulder stability, as well as throwing speed and throwing accuracy. After the conditional survey, 18 players were selected for the intervention group (IG) and 18 players for the control group (CG). Significant relationships were found between the medial stability of the shoulder joint (Y-balance) and throwing accuracy (upper right corner) (r = 0.766; p &lt; 0.001), throwing accuracy (upper left corner) (r = 0.729; p &lt; 0.001), total throwing accuracy (r = 0.907; p &lt; 0.001). The IG showed significant improvement in trunk stability (p &lt; 0.001), shoulder joint stability (p &lt; 0.001), throwing velocity (p &lt; 0.001), and throwing accuracy (p = 0.002), compared to the CG. These findings support the idea that trunk and shoulder stability are related to throwing performance of female handball players. Measuring and training these aforementioned factors, particularly medial shoulder stability, may be a valuable adjunct to improving throwing accuracy and throwing velocity.

Effectiveness of monopolar diathermy by radiofrequency combined with exercise in patients with chronic low back pain: A randomized clinical trial.

Chronic low back pain can severely affect quality of life. While several treatments are available, the combination of therapies often results in better outcomes. This study delves into the comparative effectiveness of combining monopolar dielectric diathermy radiofrequency (MDR) with supervised therapeutic exercise against the latter treatment alone. A randomized single-blind controlled trial was conducted. The intervention group (n= 30) received MDR with supervised therapeutic exercises for eight weekly sessions for four weeks. The control group (n= 30) received only the same exercise protocol. The following self-report measures were assessed before the first treatment session, at four, and 12 weeks: disability, pain, kinesiophobia, quality of life, sleep quality, emotional distress, isometric trunk strength, and trunk flexion range. Repeated ANOVA measures revealed significant time*group interactions for the McQuade test (p= 0.003), the physical role (p= 0.011), vitality (p= 0.023), social function (p= 0.006), and mental health subscales (p= 0.042). Between-group analyses showed significant differences for all outcomes at each follow-up: RMDQ (post-treatment, p= 0.040), ODI (post-treatment and 12-week, p= 0.040), VAS (p< 0.001), TSK (p< 0.001), and McQuade Test (p< 0.020). The combination of diathermy radiofrequency with supervised therapeutic exercise significantly surpasses the efficacy of supervised therapeutic exercise alone, showcasing improvements in pain, disability, kinesiophobia, lumbar mobility in flexion, and overall quality of life in patients with chronic low back pain.

Functional priorities of individuals with spinal cord injury: a Saudi Arabian perspective.

People with spinal cord injury (SCI) are the deciding force behind the rehabilitation program to improve their quality of life (QoL) based on their personal preferences. Here we aimed to determine the preferences perceived most vital by Saudi SCI population to improve their QoL, and explore if these preferences are affected by gender, education, and duration, level, or extent of injury. Participants ranked seven priorities of bodily functions as Rank I-VII with "I" being "Most important," and "VII" being "Least important." Inpatient rehabilitation facility. 120 participants (>18 years of age) of either sex with SCI without polytrauma, acquired brain injury, neurodegenerative disease, and dementia. Ranking scale of seven priorities of bodily functions as Rank I-VII with "I" being "Most important," and "VII" being "Least important." Of 101 individuals (mean age: 35.2 ± 14.8 years) finally included, 70.3% were males, 66.3% had onset of SCI since ≥ 3 years, 48.5% had a complete injury, and 75% had paraplegia. Most (26.7%) participants ranked walking as the first priority followed by hand/arm function (20.8%). Sexual function was the least important priority (39.6%). Hand/arm function was significantly more important for individuals with tetraplegia (p < 0.001). Trunk strength and balance was significantly less important for individuals with complete injury (p = 0.037). Participants with the onset of injury < 3 years and a complete injury reported bladder/bowel function as significantly more important (p = 0.011). Walking was significantly more important for people with incomplete injury and for people with injury duration ≥ 3 years (p = 0.022, p = 0.002 respectively). The top priority in our sample of Saudi people with SCI was walking followed by hand/arm function while the least desired function was regaining sexual function. Walking was a prioritized function for people with injury duration ≥ 3 years and people with a complete injury while hand/arm function was highly prioritized by people with tetraplegia.

Trunk and shoulder strength and mobility in young female volleyball and handball athletes

IntroductionVolleyball and handball have typical overhead throwing motion that can generate adaptations in the athlete's kinetic chain predisposing to injuries and pain. Considering the importance of the trunk and shoulder in overhead throwing motion and the particularities of these action in different sports, this study aimed to compare the trunk and shoulder muscle strength and mobility in young female volleyball and handball athletes. DesignCross-sectional study with 70 female volleyball and handball athletes between 13 and 18 years old. MethodsShoulder rotators, trunk extension and flexion with rotation strength was measured with a handheld dynamometer (MicroFET 2, Hoogan Health Industries, West Jordan, UT, USA). Shoulder and trunk range of motion was measured with a digital inclinometer (Acummar – model ACU001). Total range of motion deficit (TROM deficit), glenohumeral internal and external rotation of dominant (DOM) and non-dominant (NDOM) shoulder were also calculated. ResultsHandball athletes presented greater muscle strength of trunk flexors/rotators (DOM: 24.96%, effect size: 0.687; NDOM, 31.83%, effect size: 0.798) and dominant shoulder internal rotators (16.65%, effect size: 0.619). The groups showed no difference for trunk and shoulder range of motion and external rotators strength. A TROM (volleyball: 48%, handball: 35%) and a glenohumeral internal rotation deficit (volleyball: 28%, handball: 29%) was found in both groups. ConclusionsYoung female handball athletes have greater strength of trunk flexors/rotators and dominant shoulder internal rotators compared to volleyball athletes. These differences may be related to the different demands required in the movement of these sports.

Injury Profiles of Elite, Semielite, and Recreational Golfers, and Their Associated Risk Factors: A Systematic Review

Abstract Garrett, JM, Beaumont, PL, van den Hoek, DJ, Veugelers, K, Schmitz, M, and Bennett, H. Injury profiles of elite, semielite, and recreational golfers, and their associated risk factors: a systematic review. J Strength Cond Res 38(6): 1157–1176, 2024—Golf is one of the most participated sports played worldwide. However, how injury distributions change between different golf populations is unknown, and associated injury risk factors are unclear. Therefore, this review aimed to describe the common musculoskeletal injuries in different golf populations and identify their associated risk factors. A systematic search was performed to identify eligible articles through PubMed, SPORTDiscus, EMBASE, and Scopus up until September 4, 2023. Of the 4643 studies identified, 58 satisfied the inclusion criteria. Data from 10,437 subjects were extracted, with the most common area of injury to all golf populations being the lower back. Different injury distributions were found between populations with elite male golfers (n = 1924 injuries, 62% of all injuries) and recreational male golfers (n = 442 injuries, 45% of all injuries) reporting the trunk as the most injured region, whereas upper-extremity injuries were the most prevalent injury in elite female golfers (n = 890 injuries, 42% of all injuries) and recreational female golfers (n = 178 injuries, 47% of all injuries). Range-of-motion deficits at the hip and spine were identified as risk factors for elite golfers, whereas measures of lower-limb and trunk strength endurance were identified as risk factors for recreational golfers, suggesting areas of focus for golf practitioners. However, there is a paucity of robust studies evaluating the epidemiology of musculoskeletal injuries in all golf populations, and because of the variety of methods and measures used, detailed comparisons and definitive recommendations were difficult to make. Nonetheless, this review provides an overview of the common golf injuries and possible risk factors, which can aid partitioners in developing strategies for injury prevention for all golfing demographics.

CSP2023: 332 - Hand-held dynamometry is a reliable and valid to evaluate trunk strength in people with and without chronic low back pain

CSP2023: 332 - Hand-held dynamometry is a reliable and valid to evaluate trunk strength in people with and without chronic low back pain

Factors Affecting Shooting Performance in Laser Run

Abstract Purpose Laser Run combines running and shooting with a laser pistol in multiple laps with high cardio-vascular stress. The aim of this study was to analyze the impact of shooting rate, shooting rhythm, heart rate, and core stability on the overall performance. Methods During a qualification race with 23 elite athletes heart rate and shooting performance were measured. The shooting rate and rhythm were then calculated and trunk strength endurance was determined in a separate test. Results Firing an average of 10.2 ± 3.9 shots per lap, the athletes spent a mean of 23.0 ± 12.0 s at the shooting range. The mean shooting rate was approximately 2.4 s between two shots. The results indicated a regular shooting rhythm to be more important than high shooting rate. The variation of the shooting rate showed a strong correlation with the overall shooting performance (r = 0.77). Athletes shoot at a heart rate close to 95% of their maximum heart rate. However, deviations do not seem to influence on the shooting performance, whereas core strength endurance obviously has a strong impact on shooting performance (r = −0.57). Conclusion Athletes must train to shoot with high heart rates and find a balance between high shooting rate and precision. A constant shooting rhythm and good core stability appear to be particularly important for high performance.

The reliability, variability and minimal detectable change of multiplanar isometric trunk strength testing using a fixed digital dynamometer

ABSTRACT Trunk strength plays a vital role in athletic performance, rehabilitation and general health, however, current assessment methods are expensive, non-portable or unreliable. This study aimed to investigate the within- and between-session reliability, variability, standard error of measurement and minimal detectable change (MDC) of trunk strength in the sagittal (flexion and extension) and frontal planes (left and right lateral flexion) using a fixed digital dynamometer. Eighteen participants (ten men and eight women) attended two sessions separated by 7 days. Participants were fitted with a trunk harness which was secured to an immovable base via a digital dynamometer. Three maximal voluntary isometric contractions were completed across four positions (prone, supine, left-side recumbent and right-side recumbent, respectively) on a glute-hamstring raise machine. All positions demonstrated excellent reliability and low variability within session (ICC: 0.95–0.98; CV: 5–7%) and between sessions (ICC: 0.98–0.99; CV: 4–6%), across all positions. The between-session MDC ranged from 8% (prone) to 13% (right-side recumbent), translating to absolute values between 2.9 and 3.2 kg across all positions. Maximal isometric force testing using a fixed digital dynamometer provides reliable measurements of multiplanar trunk strength, providing a practical method for use in clinical practice.

Exploring the interplay of trunk and shoulder rotation strength: a cross-sport analysis.

Introduction: Trunk and shoulder strength are consistently shown to be involved in performance limitations, as well as contributing to stability, power output, and reducing the risk of injury. Although their biomechanical interaction is a critical aspect for athletes, there is limited research on the relationship between trunk and shoulder strength in sports where upper body mechanics are critical for optimal performance. Purpose: This study examined the differences and relationships between trunk rotational strength and shoulder rotational strength among athletes participating in mixed martial arts (MMA), tennis, swimming, and baseball. Methods: Maximal voluntary contraction tests were performed to evaluate strength of 39 professional adult male athletes from disciplines of MMA (n = 6), tennis (n = 11), swimming (n = 11) and baseball (n = 11). Peak force data were used in sports comparison and relationship analysis between trunk and shoulder rotation strength parameters. Results: The findings revealed a complex and significant relationship between trunk and shoulder strength, with unique patterns for each athletic discipline. Tennis players exhibited a strong correlation between trunk bilateral differences and internal shoulder rotation, while other disciplines demonstrated a more balanced use of trunk asymmetry. Swimmers displayed the best interactions between trunk and shoulder overall, emphasizing the aquatic environment's biomechanical demands. In MMA, the strongest correlation was between shoulder internal and external rotation with the trunk, mainly due to the number of defensive movements in addition to offensive ones. Baseball pitchers showed a significant correlation between internal/external shoulder rotation strength ratio and trunk asymmetry. Conclusion: While no differences in peak force variables were found, unique relationships between trunk and shoulder rotational performance were discovered. The results suggest a long-term sport-specific adaptation of the trunk-shoulder interaction in sports that require upper limb power movements. It seems, that the relationship between the various parameters of trunk and shoulder was influenced by the movement stereotype of each sport. Therefore, recognition of sport-specific interactions is critical to the development of effective training programs that enhance performance and potentially reduce injury risk in different sports. Researchers and practitioners should focus on longitudinally monitoring fluctuations in TRS and SRS relationships throughout each sport season and examining potential associations with injury incidence.

Application Research of Functional Movement Screen in Weightlifting Athletes

This study aimed to investigate the functional movements and the causes of injuries of weightlifting athletes by Functional Movement Screen test, and improve the physical training approaches for weightlifting athletes. Six weightlifting athletes from Hainan Provincial Sports Academy were screened for the Functional Movement Screen test. The test results were evaluated and analyzed by the researchers. The test items included the shoulder flexibility, the active straight leg raise, the trunk stability push-up, the rotary stability test, the deep squat, the hurdle step and the inline lunge. The average score of weightlifting athletes was 15.5 points. The average score for the inline lunge was 3 points, the hurdle step had an average score of 2.8 points, but the average score for shoulder flexibility was less than 1 point. The trunk strength and lower limb strength of weightlifting athletes were at relatively high levels, but shoulder flexibility was relatively weak.

IJCM_218A: Association between school bag weight and trunk strength among children in Mangalore

Background: School bags serve as a practical means for students to transport essential academic materials and personal items, including food. The significance of school bag weight has garnered increased attention in recent years due to its potential impact on the musculoskeletal health of school children. Excessive school bag weight has been identified as a significant contributor to various health issues, ranging from neck pain and shoulder discomfort to headaches, general fatigue, decreased muscle strength, and, notably, back injuries among children. Methods: The study involved 178 school children in Mangalore, ranging from 10-15 years, for a period of 23 days. School bag weights were measured using calibrated scales, and trunk strength was assessed using a hand held dynamometer. Statistical analysis, including Chi-square test, student’s ‘t’ test and Karl Pearson correlation test were employed to identify any significant relationships between these variables. Results: Preliminary findings revealed a positive correlation between school bag weight and trunk strength among the participants. Results indicated that a considerable proportion (83.1%) of students were burdened with an excessive load of bags. The evaluated muscular strength was discovered to be diminished in these individuals, and they experienced symptoms that were interconnected, highlighting the potential impact of school bag weight on the musculoskeletal health of children in Mangalore. Conclusion: These findings advocate measures to alleviate the burden on children’s musculoskeletal health. Further research and interventions are warranted to promote a balanced and healthy school environment for the well-being of the younger generation.

Gender-specific reference values of dynamometric and non-dynamometric trunk performance in individuals with different body fat percentages: A preliminary study.

Trunk muscles maintain steady effort with adequate strength and endurance. When the muscle performance is subpar, it might cause lower back discomfort. No reference for trunk strength and endurance has been established previously. The aim of this study was to determine the normative reference values for dynamometric and non-dynamometric tests in people with various body fat percentages. Two hundred sixty-four participants aged 19-40 years old were recruited in this cross-sectional study. The Siri equation was used to calculate the individuals body fat proportions, which were divided into normal, high, and very high body fat for men and women. The Modified Sorenson's and the Back-Leg-Chest Dynamometric tests were utilized to measure muscular performance. The means of strength in females with normal, high, and very high body fat percentages were 27.39, 25.75, and 25.37 N/m2, respectively. The males in the same category had the means of 56.48, 51.79, and 60.17 N/m2, respectively. The highest mean of endurance in females was in those with normal body fat percentage (42.28), so did males (71.02). Our findings suggest that males had higher trunk muscle strength and endurance than females, and normal-body-fat individuals had the greatest endurance regardless of gender.

Maximal Exercise Tolerance, Objective Trunk Strength, and Mobility Measurements in Axial Spondyloarthritis.

Although exercise therapy is safe, effective, and recommended as a nonpharmacological treatment for axial spondyloarthritis (axSpA), there is a lack of guidelines regarding type and dosage. Insufficient knowledge about physical and physiological variables makes designing effective exercise programs challenging. Therefore, the goal of this study was to simultaneously assess trunk strength, spinal mobility, and the cardiorespiratory fitness of patients with axSpA. In a cross-sectional study, 58 patients with axSpA (mean age 40.8 yrs, 50% male, mean symptom duration 10.3 yrs) performed maximal cervical and trunk mobility and isometric strength tests in all planes (using David Back Concept devices) and a maximal cardiopulmonary bicycle exercise test (n = 25). Mobility and strength data were compared to healthy reference data. Cut-off values for clinical cardiopulmonary exercise testing interpretation were used to judge normality. Patients were compared based on radiographic involvement and symptom duration. Both strength (P ≤ 0.02) and mobility (P ≤ 0.001) were significantly lower for the patients with axSpA compared to the reference. Strength deficits were comparable between the radiographic and nonradiographic groups (P > 0.05, except trunk extension [P = 0.03]), whereas mobility showed higher deficits in the radiographic group (cervical extension [P = 0.02] and rotation [P = 0.01], and trunk extension [P = 0.03] and rotation [P = 0.03]), regardless of symptom duration. Similarly, symptom duration positively affected oxygen pulse (P = 0.03), relative anaerobic threshold (P = 0.02), and aerobic capacity (P = 0.02). In patients with axSpA, strength is more affected than mobility when compared to healthy controls. Likewise, mainly the metabolic component of aerobic capacity is impaired, affecting cardiopulmonary fitness. These findings indicate that future personalized exercise programs in patients with axSpA should incorporate exercises for cardiopulmonary fitness next to strength and mobility training.

Biomechanical gait analysis and rehabilitation in a traumatic hallux deficit patient: a case report

BackgroundThe hallux plays a crucial role in maintaining standing balance and facilitating forward and backward movements during gait.Case presentationA 21-year-old Japanese patient, suffering from a traumatic hallux deficit with only a portion of the basal phalanx intact, underwent rehabilitation treatment. The thenar area exhibited instability, leading to impaired balance and walking difficulties. Biomechanical assessment revealed the need for a rehabilitation strategy for the foot, as well as the knee, hip, and trunk. A rehabilitation protocol was designed to enhance medial foot loading during walking and standing, including balance and trunk strength training. After a 12-week rehabilitation period, the patient’s gait showed significant improvement. Specifically, the load response and single-support phases of the gait cycle on the affected side increased from 46.9% to 49.3%, while the pre-swing phase decreased from 14.6% to 11.6%. The vertical component of the ground reaction force rose from 599.8 to 647.5 N. The enhanced stability from balance training and increased muscle strength contributed to the patient’s improved walking and balance.ConclusionA patient with a traumatic hallux deficit underwent conservative treatment through strategic rehabilitation according to biomechanical assessment. This case report underscores the value of biomechanical gait analysis in the conservative management of similar conditions.

Relationships of lower extremity and trunk asymmetries in elite soccer players.

In light of previous research highlighting the prevalence of asymmetries in soccer players and possible links to injury risks, there is a crucial gap in the biomechanical understanding of complex relationships between lower extremity and trunk asymmetries in elite soccer players. The purpose of this study was to investigate the level, relationships, and differences among twelve different parameters of strength, morphological, and neuromuscular asymmetries in elite soccer players. Methods: Elite male soccer players (n = 25, age 21.7 ± 3.9years) were tested in the following tests: bilateral fluid distribution, hip flexor range of motion, postural stability, isokinetic strength of knee extensors and flexors, isometric lateral trunk rotation strength, eccentric strength of knee flexors, isometric bilateral strength of hip adductors, and vertical ground reaction force in counter-movement jump-free arms, counter-movement jump, squat jump, and drop jump tests. One-way ANOVA, Pearson's coefficient (r), and partial eta squared (η p 2) were used for data analysis. Results: Significant differences in asymmetries were found in elite soccer players (F11,299 = 11.01, p < .01). The magnitude of asymmetry over 10% was in postural stability and drop jump parameters. The lowest magnitudes of asymmetries were in the fluid distribution of the lower limbs and the vertical ground reaction force during the take-off phase in squat jumps. The highest asymmetries between the dominant and non-dominant sides were found in postural stability and drop jump. A total of eleven significant correlations (p < 0.05, r = 0.41-0.63, R2 = 0.17-0.40) were detected between the analyzed asymmetries in elite soccer players. The lateral trunk rotation asymmetries were significantly correlated to vertical ground reaction force asymmetries and knee extensors. Conclusion: Long-term exposure in elite soccer leads to unilateral biomechanical loading that induces abnormal strength and morphological adaptations in favor of the dominant side while linking lower limb and trunk strength asymmetries. By unraveling these complex relationships, we strive to contribute novel methods that could inform targeted training regimens and injury prevention strategies in the elite soccer community. The data should encourage future researchers and coaches to monitor and develop trunk strength linked to lower body kinematics.

The Neuromuscular Parameters Affecting Static and Dynamic Balance in Adolescent Male Soccer Players with Dynamic Knee Valgus

Background and Aims The anterior cruciate ligament injury in athletes is associated with disorders related to balance and postural control. Poor balance is a predictor of lower limb injury in athletes. This study aims to investigate the different neuromuscular parameters that affect the static and dynamic balance in adolescent male football players with Dynamic Knee Valgus (DKV). Methods This is a correlational study. Participants were 83 adolescent male football players with DKV (age: 12.63±0.72 years, height: 1.69±0.07 meters, weight: 23.23±7.74 58 kg, BMI: 20.32±2.38 kg /m2), who were selected using a purposive sampling method. The presence of DKV was assessed by the squat test. The strength of the trunk and hip muscles was assessed by manual muscle testing (MMT), trunk endurance by the McGill test, and range of motion (ROM) of hip and ankle joints by a goniometer. Moreover, the static and dynamic balances were evaluated by the Bass Stick test and Y balance test, respectively. The Pearson correlation test was used to examine the relationships at a significance level of 0.05. All statistical operations were performed by SPSS software, version 24. Results The results of the present study showed a significant relationship between static balance and the study parameters (P≤0.05) except for trunk flexion strength (P=0.16) and ROM (P&lt;0.05), hip flexion ROM (P=0.83), hip extension ROM (P=0.96), hip abduction ROM (P=0.77) and ankle dorsiflexion ROM (P=0.94). The dynamic balance at anterior-posterior direction had a significant relationship with trunk endurance and left-side plank (P=0.07) and strength (P=0.05), but not with plank test score (P=0.45). The dynamic Y balance at posteromedial direction had a significant relationship with all variables except for 60° flexion (P=0.40), plank (P=0.53), left-side plank (P=0.09), and trunk extension strength (P=0.23). The results of the study also showed the significant relationship of dynamic balance at posterolateral direction and the total score of Y balance test with total trunk endurance test score (P=0.03, P=0.003) and right-side plank (P=0.005, P=0.001). Moreover, trunk extension strength and hip strength variables had a significant relationship with posterolateral dynamic balance and total Y balance test score (P≤0.05). Furthermore, the ROM of ankle dorsiflexion had a significant relationship with balance at the posteromedial (P=0.03), posterolateral (P=0.02) directions and the total Y balance score (P=0.02). Conclusion Static balance of adolescent male soccer players with DKV has a significant relationship with trunk endurance, trunk strength and thigh strength. There is a significant relationship between dynamic balance and trunk endurance, trunk strength, hip strength, and ankle dorsiflexion ROM.

Relative Age Effect for Different Playing Positions in Adolescent Female Volleyball Players

Understanding the Relative Age Effect (RAE) in female volleyball can provide a deeper insight into potential developmental advantages and selection biases between playing positions and volleyball-related performance characteristics. This study aimed to investigate the occurrence of the RAE in adolescent female volleyball players according to the playing position and the possible differences in anthropometric and performance characteristics between the relative age groups. The study involved 193 young female volleyball players from 12 different regions and 108 sports clubs from all over Greece, with an average age of 14.53 ± 0.31 years, height of 1.67 ± 0.07 m, weight of 57.20 ± 9.10 kg, and body mass index (BMI) of 20.34 ± 2.50. RAE was identified by the birth quarter of each player, categorizing thus the total sample into four sub-groups: Q1 (January–March), Q2 (April–June), Q3 (July–September), and Q4 (OctoberDecember). Anthropometrics, upper and lower limb power, agility, flexibility, and trunk strength were also assessed. The distribution of volleyball players differed significantly across birth quarters (34.19% of Q1, 25.9% of Q2, 22.79% of Q3, 17.09% of Q4; χ2 = 11.788, p = 0.008). Analysis revealed no significant association between birth quarter and playing position (χ2 = 11.314, p = 0.730). Present study’s results indicated no RAE in young female volleyball players regarding their playing position. Also, performance tests did not differ significantly among the RAE groups. Moreover, despite athletes’ early specialization based on assigned playing positions, no differences in athletes’ position-related performance characteristics were observed. These findings suggest that interventions to mitigate RAE should be considered to ensure equitable development opportunities across all playing positions.

Physiological Profiles of Male and Female CrossFit Athletes.

To (1)establish extensive physiological profiles of highly trained CrossFit® athletes using gold-standard tests and (2)investigate which physiological markers best correlate with CrossFit Open performance. This study encompassed 60 participants (30 men and 30 women), all within the top 5% of the CrossFit Open, including 7 CrossFit semifinalists and 3 CrossFit Games finalists. Isokinetic dynamometers were employed to measure maximum isometric and isokinetic leg and trunk strength. Countermovement-jump height and maximum isometric midthigh-pull strength were assessed on a force plate. Peak oxygen uptake (VO2peak)was measured by a cardiopulmonary exercise test, and critical power and W' were evaluated during a 3-minute all-out test, both on a cycle ergometer. Male and female athletes' median (interquartile range) VO2peak was 4.64 (4.43, 4.80) and 3.21 (3.10, 3.29) L·min-1, critical power 314.5 (285.9, 343.6) and 221.3 (200.9, 238.9) W, and midthigh pull 3158 (2690, 3462) and 2035 (1728, 2347) N. Linear-regression analysis showed strong evidence for associations between different anthropometric variables and CrossFit Open performance in men and women, whereas for markers of cardiorespiratory fitness such as VO2peak, this was only true for women but not men. Conventional laboratory evaluations of strength, however, manifested minimal evidence for associations with CrossFit Open performance across both sexes. This study provides the first detailed insights into the physiology of high-performing CrossFit athletes and informs training optimization. Furthermore, the results emphasize the advantage of athletes with shorter limbs and suggest potential modifications to CrossFit Open workout designs to level the playing field for athletes across different anthropometric characteristics.